Secondary Timing

Discussion of the Aerovee kit engine.

Re: Secondary Timing

Postby GraemeSmith » Tue Aug 03, 2021 6:48 pm

Area 51% wrote: so that's a smidge over 4deg per tooth.


Thanks!

Though now I am looking for a protractor scaled in "smidges"......
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Re: Secondary Timing

Postby Area 51% » Wed Aug 04, 2021 6:45 am

Down here in Florida, a smidge is .0909. Up north you have the contraction factor which is equal to the square of the hypotenuse times the slow blow hole.
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Re: Secondary Timing

Postby Scott Todd » Wed Aug 04, 2021 9:21 am

And it changes out west where the temperatures are over 100F half the year! Those darn Sin, Cos, and Tan get involved.

An old fashion timing light is your friend ;)
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Re: Secondary Timing

Postby Bryan Cotton » Wed Aug 04, 2021 9:26 am

GraemeSmith wrote:
Area 51% wrote: so that's a smidge over 4deg per tooth.


Thanks!

Though now I am looking for a protractor scaled in "smidges"......

I would have thought the smidge was a unit of measurement we inherited from the UK, and then never let go. You know, like all our other measurements.
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Re: Secondary Timing

Postby WesRagle » Wed Aug 04, 2021 10:19 am

Bryan Cotton wrote:I would have thought the smidge was a unit of measurement we inherited from the UK, and then never let go. You know, like all our other measurements.


It's kind'a like calibrating your airspeed indicator in "Furlongs per Fortnight".

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Re: Secondary Timing

Postby GraemeSmith » Wed Aug 04, 2021 11:29 am

Bryan Cotton wrote:I would have thought the smidge was a unit of measurement we inherited from the UK, and then never let go. You know, like all our other measurements.

I can assure you that in Scotland (from whence I originate) we never used the "smidge". We used "the thinness of a haggis's b@ll hair". Ahem...

Now - anyone want to answer my question about the mag drop?.... :-)
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Re: Secondary Timing

Postby Area 51% » Wed Aug 04, 2021 2:08 pm

I don't know how you could reasonably expect a 0 rpm drop after shutting off one of the mags unless it was faulty and wasn't pulling it's weight.

Based on the semi-shielded location of the bottom plugs and a relocated flame front, I don't know if you can expect an equal drop between the two mags in the first place. That's why my money is on the 50rpm differential between the two.

Having said all that, I couldn't get the bottom magnatron wires to reach the top rear plugs without adding to the wires. So I have them firing the bottom rear plugs while the upper magnatron fires the upper fronts. So I have a more or less apples to apples comparison between the ignitions sources.

The drop is 50 on either source. The difference is 0.
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Re: Secondary Timing

Postby Arjay » Thu Aug 05, 2021 10:32 am

I recall when building missiles, a typical lab designation for a very small dimension was”rch” or “red c_ _ _ hair”. Anything close to a “smidge”?

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Re: Secondary Timing

Postby Area 51% » Thu Aug 05, 2021 11:36 am

RPH.....rch......smidge......haggis'......frog hair.......any others?
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